In the original version of the Data Descriptor the surname of author Hesham Elhalawani was misspelled. This has now been corrected in the HTML and PDF versions.
Purpose: The physical properties of proton therapy allow for decreased dose delivery to nontarget structures. The purpose of this study was to determine if this translates into a clinical benefit by comparing acute and chronic morbidity between patients with nasopharyngeal carcinoma who are treated with intensity-modulated proton therapy (IMPT) and those treated with intensity-modulated radiation therapy (IMRT). Materials and Methods: Patients receiving IMPT for nasopharyngeal cancer from 2011-13 were matched in a 2:1 IMPT to IMRT ratio. Matching criteria were, in order, T-stage, N-stage, radiation dose, chemotherapy type, World Health Organization classification, sex, and age. Results: Ten patients treated with IMPT and 20 matched patients treated with IMRT were included. By the end of treatment, 2 IMPT-treated patients (20%) and 13 IMRTtreated patients (65%) required gastrostomy tube (GT) insertion (P ¼ .020). Patients receiving IMPT had significantly lower mean doses to the oral cavity, brainstem, whole brain, and mandible. Increased mean dose to the oral cavity was associated with a higher rate of GT placement (P , .001), but mean dose to the brainstem, whole brain, and mandible was not. Partitioning analysis showed that no patient required GT insertion if the mean oral cavity dose was ,26 Gy, but all patients with a mean oral cavity dose. 41.8 Gy required GT insertion. Treatment type (IMPT versus IMRT), induction chemotherapy (yes versus no), mean oral cavity dose, mean brainstem dose, and mean mandible dose were entered into the multivariable model. Only higher mean oral cavity dose remained significantly associated with higher GT rates on multivariable analysis http://theijpt.org
Computed tomography (CT) was used to study fat distribution in three groups of women of comparable age: 39 healthy volunteers, 15 patients with anorexia nervosa, and seven with Cushing syndrome. Patients with anorexia nervosa had a fivefold decrease in subcutaneous fat and only a twofold decrease in intraabdominal fat compared with the values for the volunteers. Patients with Cushing syndrome had less than a twofold increase in subcutaneous fat and greater than a fivefold increase in intraabdominal fat compared with values for the healthy subjects. These findings suggest that fat in different body compartments responds differently to disease processes and that CT can be used to measure these changes.
Summary
Radiation therapy plays an integral role in the management of head and neck cancers (HNCs). While most HNC patients have historically been treated with photon-based radiation techniques such as intensity modulated radiation therapy (IMRT), there is a growing awareness of the potential clinical benefit of proton therapy over IMRT in the definitive, postoperative and reirradiation settings given the unique physical properties of protons. Intensity modulated proton therapy (IMPT), also known as “pencil beam proton therapy,” is a sophisticated mode of proton therapy that is analogous to IMRT and an active area of investigation in cancer care. Multifield optimization IMPT allows for high quality plans that can target superficially located HNCs as well as large neck volumes while significantly reducing integral doses. Several dosimetric studies have demonstrated the superiority of IMPT over IMRT to improve dose sparing of nearby organs such as the larynx, salivary glands, and esophagus. Evidence of the clinical translation of these dosimetric advantages has been demonstrated with documented toxicity reductions (such as decreased feeding tube dependency) after IMPT for patients with HNCs. While there are relative challenges to IMPT planning that exist today such as particle range uncertainties and high sensitivity to anatomical changes, ongoing investigations in image-guidance techniques and robust optimization methods are promising. A systematic approach towards utilizing IMPT and additional prospective studies are also necessary in order to more accurately estimate the clinical benefit of IMPT over IMRT and passive proton therapy on a case-by-case basis for patients with sub-site specific HNCs.
In this large survey study, OPC survivors with late LCNP reported worse cancer treatment-related symptoms, a finding suggesting an association between late LCNP and symptom burden. This research may inform the development and implementation of strategies for LCNP surveillance and management.
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